Modern building construction techniques focus on quick and efficient building designs which use low cost readily available materials. A particular type of building design which is popular for commercial and industrial buildings consists of an internal steel framework on which cladding is mounted to form the building enclosure. Although various types of cladding can be used, one preferred type of cladding is concrete panel cladding. These concrete panels can be moulded or pre-cast in advance, and then erected onto the metal frame at the building site. Alternatively, these concrete panels may be cast on the site and once sufficiently cured, erected in place on the building frame.
Such concrete panels come in a variety of sizes with many different types of exterior finishes. To produce such panels requires an appropriately sized and shaped mould in order to produce the desired size and shape of panel. The panels may be pre-tensioned, post-tensioned or otherwise reinforced with reinforcing steel. The panels are placed side by side and one on top of another in order to form an external skin on the building. They may be placed on bracket mounts and are bolted or otherwise attached to the metal framework.
The panels are typically made in advance and stored until needed. This means that the panels must be manoeuvrable. However, it is more efficient to have several large panels rather than many small ones. Therefore, the panels tend to be large and can weigh thousands of pounds. Typically, lifting loops are provided on the panels to permit the panels to be lifted by lifting equipment and positioned in place. However, since the panels must sit side by side and one on top of another, such lifting loops are typically recessed and formed within a void space in the edges of the panel, to permit the panels to be butted up close one to another. In order to fit a lifting hook into the lifting loop the void is necessary around the recessed lifting loop. Recessed lifting loops may be provided on the top, bottom sides or ends of the panel. Typically, at least two recessed lifting loops are provided on a side, and a single recessed lifting loop is provided along a top edge. This permits the panel to be lifted by a series of lifting hooks which hold the panel in a stable manner to permit it to be easily positioned by the lifting equipment, such as a crane, onto a vehicle carrier and then eventually in place on the exterior of a building.
In the past, shaped Styrofoam® has been used during the moulding step to form a void around the recessed lifting loops. The Styrofoam® however, while providing an adequate sized and shaped void space, is messy, expensive and awkward to use.
Typically what is required is to obtain large sheets of Styrofoam® from a Styrofoam® supplier which are then individually cut into the necessary void shape. Cutting Styrofoam® sheets takes time, and typically creates highly statically charged particles which tend to stick to all surfaces. As a result, Styrofoam® particles can become stuck to surfaces of the concrete where they can create blemishes if not removed prior to the concrete setting.
A further problem of the Styrofoam® inserts is that they are difficult and awkward to remove from the cured concrete product. Essentially, the Styrofoam® needs to be chipped out of the void by hand, which creates additional electro static debris and is messy, time consuming and expensive. Further, the concrete is rough and workers can scrape their hands as they pick the Styrofoam® out of the finished product in order to create the intended void. Even once removed, the broken bits of Styrofoam® need to be swept up and disposed of, which is both time consuming and expensive.